1. Field of the Invention
The present invention relates to an optical recording and reproducing system. More particularly, it concerns an optical recording and reproducing system that can record and reproduce a large capacity of data.
2. Description of the Related Art
A prior optical recording and reproducing system having an optical recording and reproducing device arranged on one surface side of an optical recording medium and an magnetic recording and reproducing head arranged on the other surface side was put on the market. The prior system was disclosed was disclosed, for example, in an article entitled "Newly Developed Technologies for Audio Equipments", Association of Japan Television Engineering, Vol. 47, No. 6, pp. 841-844 (1993). The prior system has the magnetic optical recording and reproducing head arranged to record or reproduce a single continuous recording track on a rotating disc.
Also, the Japanese Patent Application Laid-Open No. 62-287428 disclosed an optical card recording and reproducing method having an optical card used as recording medium. In the prior method, an optical head is revolved to record on or reproduce from short arc-formed tracks of the optical card successively.
Further, the Japanese Patent Application Laid-Open No. 63-53726 disclosed an optical recording and reproducing system having a tape-formed optical recording medium and a rotating optical head. The prior system records on or reproduces from short arc-formed tracks of the tape successively.
Furthermore, the Japanese Patent Application Laid-Open No. 1-285024 disclosed system for recording and reproducing having a rotating cylinder including an optical head. The prior system records on or reproduces from short arc-formed or linear tracks of an optical tape successively while the optical tape is spirally wound on the rotating cylinder. However, the prior optical recording and reproducing system in the article "Newly Developed Technologies for Audio Equipments" does not take into account recording and reproducing a large capacity of data. To record and reproduce the large capacity of data, the rotating disc as recording medium has to be made larger or has to be increased in the number. Making largely the rotating disc needs a larger system that causes a problem of noises and vibration. Increasing the number of rotating discs causes a problem of interruption of signal when the rotating disc is put out and in. The prior art also has the disadvantage that it is hard to store the increased number of rotating discs if these record large capacity of data such as a high definition television signal in the future. Usual magnetic recording and reproducing systems such as video tape recorder have to be made to have as narrow a track as a few .mu.m to record in high density. It is difficult to have such a narrow track as vibration is caused and the medium feeding speed is changed when the head is moved to scan.
The prior arts disclosed in The Japanese Patent Application Laid-Opens mentioned above do not take into account the high accuracy and reliability of focusing and tracking that are indispensable to secure continuity of a plurality of short tracks.